Due to the wide range of ways how parameters can be supplied, we deliberately ignored one rule of the specification, which requires non-official features to be defined in a non-null namespace URI. In the following, we will indicate which features are specific to our implementation.
The namespace for serialization parameters is statically bound to the {{Code|output}} prefix. This means that it need not (but may) be declared in the query prolog:
<syntaxhighlight lang="xquery">
declare namespace output = 'http://www.w3.org/2010/xslt-xquery-serialization';
declare option output:method 'text';
<xml>Hi there</xml>
</syntaxhighlight>
=Parameters=
<syntaxhighlight lang="xquery">
(: The output namespace declaration is optional, because it is statically declared in BaseX) :)
declare namespace output = "http://www.w3.org/2010/xslt-xquery-serialization";
declare option output:method "csv";
declare option output:csv "header=yes, separator=semicolon";